Recovery of Native Bonneville Cutthroat Trout in Right-hand Fork

USGS Cooperative Research Unit Corner

Recovery of Native Bonneville Cutthroat Trout in Right-hand Fork

Scientists with the USGS Utah Cooperative Fish and Wildlife Research Unit are leading research on Utah’s native fish, the Bonneville cutthroat trout, a fish feared extinct in the 1970s. Researchers have monitored for fish abundance, density, distribution, size and age for nearly two decades. State managers found that the Bonneville cutthroat trout was still in Utah’s rivers and streams, but the sub-species was imperiled and had experienced dramatic reductions in abundance and distribution rangewide.

Bonneville Cutthroat Trout

For over a decade, managers and anglers worked to keep the fish off the endangered species list. In 1997, to ensure the long-term conservation of the state fish in Utah, four federal agencies, two state agencies, and the Goshute Tribe came together to create and sign the Conservation Agreement for Bonneville Cutthroat Trout in the State of Utah.

The signers of the agreement rely heavily on ongoing, research and monitoring about important populations and the trout’s environment to make good management decisions. With these data, managers can focus their restoration efforts on areas where they are most likely to succeed.

One such location is the Right-hand fork, a tributary of the Logan River located in the mountains of Northern Utah. Prior to 2013, the Right-hand fork was brimming with exotic and invasive brown trout. In 2002, the Utah Unit (Phaedra Budy’s Lab) recorded 4,000 brown trout per kilometer in the tributary – denser than any other recorded population on earth. This exotic fish pushed out native trout.

Brown trout thrive in Right-hand fork because of the creek’s abundance of spawning gravel, beaver dam ponds, and bugs; but the principal reason why trout flourished here is that the stream is spring fed. The spring stabilizes the water temperatures year round keeping it cooler in the summer and warmer in the winter, which promotes fish growth and survival. The springs are also prone to be chemically rich and stimulate primary production and secondary production such as bugs.

Budy hypothesized the dense population of brown trout were overflowing into the main leg of Logan River, increasing the exotic trout population there. She predicted if managers could replace the brown trout with a population of Bonneville cutthroat trout, these native fish would thrive. Once the native trout population were recovered and robust, they too would begin to overflow into the main arm of the river and increase the native trout’s population throughout Logan River.

In about 2010, a partnership of the Utah Division of Wildlife Resources, U.S. Forest Service, Cache Anglers, and Utah State University began taking steps for recovering the Bonneville cutthroat trout in the tributary. In 2013, they used a chemical treatment to remove the brown trout from the Right-hand fork. To ensure the exotic trout would not re-enter Right-hand fork, researchers installed structures at the mouth of the tributary allowing trout to exit but not return.

The new population of Bonneville cutthroat trout had to come from the Logan River, so the genetics would remain the same. Paul Thompson, deputy director of the Recoveries Program in Utah’s Department of Natural Resources said, “Because [the Logan River] has whirling disease we couldn’t move live fish, so we collected eggs from the spawning fish in Temple fork, another tributary of the Logan River.”

The Cache Anglers played a large role in the relocation of these trout. Budy explains, “Removing [the eggs and embryos] then restocking the juveniles was largely the responsibility of the Cache Anglers. They did a wonderful job.”

It has been over 50 years since managers feared the Bonneville cutthroat trout were extinct, but with ongoing conservation, managers and anglers have helped restore the trout to 40 percent of its historic range. The fish are now thriving in the Right-hand fork with multiple age classes and big, fat, catchable native trout. This pleases fly-fishermen – the tributary is now a pristine habitat for the Bonneville cutthroat trout and a blue ribbon fishery.

Brett Roper, a fisheries biologist with the Forest Service and avid fly fisherman said, “A nice thing about fishing for Bonneville Cutthroat Trout in the Logan River – it is right out my back door. In less than 30 minutes I can be casting over water so clear I can often watch these trout as they move to intercept my fly. When I get one of these fish in my hands, the beauty of the spotting pattern, the red slash under its gills, and the fact it truly is the native trout of the region, makes me thankful I still have the opportunity to pursue these fish.”

The ONB features articles from Cooperative Fish and Wildlife Research Units across the country. Working with key cooperators, including WMI, Units are leading exciting, new fish and wildlife research projects that we believe our readers will appreciate reading about. This article was written by Shauna Leavitt, USGS Utah Cooperative Fish and Wildlife Research Unit, Quinney College of Natural Resources.

Photo Credit
USGS Utah Cooperative Fish and Wildlife Research Unit
March 16, 2018